Index: /trunk/ippconfig/gpc1/ppImage.config
===================================================================
--- /trunk/ippconfig/gpc1/ppImage.config	(revision 42765)
+++ /trunk/ippconfig/gpc1/ppImage.config	(revision 42766)
@@ -1139,4 +1139,30 @@
 END
 
+# CZW 2018-02-14
+# The default PPIMAGE_N includes BACKGROUND=T, and that breaks detrend construction
+PPIMAGE_N          METADATA
+  BASE.FITS        BOOL    TRUE            # Save base detrended image?
+  BASE.MASK.FITS   BOOL    FALSE           # Save base detrended image?
+  BASE.VARIANCE.FITS BOOL    FALSE           # Save base detrended image?
+  CHIP.FITS        BOOL    FALSE           # Save chip-mosaic-ed image? 
+  CHIP.MASK.FITS   BOOL    FALSE           # Save chip-mosaic-ed image? 
+  CHIP.VARIANCE.FITS BOOL    FALSE           # Save chip-mosaic-ed image? 
+  OVERSCAN         BOOL    FALSE           # Overscan subtraction
+  NONLIN           BOOL    FALSE           # Non-linearity correction; not implemented
+  BIAS             BOOL    FALSE           # Bias subtraction
+  DARK             BOOL    FALSE           # Dark subtraction
+  SHUTTER          BOOL    FALSE           # Shutter correction
+  FLAT             BOOL    FALSE           # Flat-field normalisation
+  MASK             BOOL    FALSE           # Mask bad pixels
+  MASK.BUILD       BOOL    FALSE           # Build internal mask?
+  FRINGE           BOOL    FALSE           # Fringe subtraction
+  PHOTOM           BOOL    FALSE           # Source identification and photometry
+  ASTROM.CHIP      BOOL    FALSE           # Astrometry per chip?
+  ASTROM.MOSAIC    BOOL    FALSE           # Astrometry for mosaic?
+  BIN1.FITS        BOOL    TRUE            # Save 1st binned chip image?
+  BIN2.FITS        BOOL    TRUE            # Save 2nd binned chip image?
+  BACKGROUND       BOOL    FALSE           # Subtract background?
+END
+
 # JPEG images for different types of residual images
 # Save JPEG from BIN1 for bias